This research will be performed primarily in the laboratory of Dr. Szczupak in the University of Buenos Aires, Argentina as an extension of the NIH grant RO 1 MH 43396. The long-term objective of the project is to understand the structural configuration of sensory-motor networks. Specifically the aim of the present proposal is to reveal the role of a specific type of neurons which operates entirely in a graded mode. This type of neurons, recognized as non-spiking neurons, are different than the majority of cells in the nervous system in that they can operate as a highly compartamentalized structure subserving different networks due to the fact that propagation of signals is not supported by regenerative processes like spike firing. Investigation of their functional role in the simple nervous system of the leech will enable to assess the physiological rote of these type of neurons and illustrate about their function in other systems.